Actions

Multiattack. The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.   Bite. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: (2d10 + 10) piercing damage.   Claw. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: (2d8 + 10) slashing damage. If the target is a Huge or smaller creature, it is grappled (escape DC 28 (10+Athletics)) and is restrained until this grapple ends. The greatwyrm can only have one creature grappled this way at a time.   Tail. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: (2d10 + 10) bludgeoning damage. If the target is a creature, it must make a DC 28 (8 +Prof + Str) Strength saving throw or be knocked prone   Frightful Presence. Each creature of the dragon's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 23 (8 + Prof + Cha) Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragon's Frightful Presence for the next 24 hours.   Summon Dawn. The dragon creates a sphere of daylight at a point the dragon can see within 120ft of it, the sphere has a radius of 10ft and it creates bright light in a 60ft radius and dim light for 60ft beyond that, any friendly creature who can see the sphere can add 1d4 to it’s attack rolls and saving throws, if the creature is in the dim light it must subtract one from the roll, if it is not within the light it must subtract two from the roll, if an enemy creature who can see the sphere must subtract 1d4 from their attacks and saves following the same rules regarding level of light. The sphere lasts for 1 minute or until the dragon uses this feature again.   Fire Breath (Recharge 5-6). The dragon exhales fire in a 300-foot cone. Each creature in that area must make a DC 28 (8 + Prof + Str) Dexterity saving throw, taking 91 (14d12) fire damage on a failed save, or half as much damage on a successful one.   Change Shape. The dragon magically polymorphs into a Humanoid or beast that has a Challenge rating no higher than its own, or back into its true form. It reverts to its true form if it dies. Any Equipment it is wearing or carrying is absorbed or borne by the new form (the dragon's choice). In a new form, the Dragon retains its Alignment, Hit Points, Hit Dice, ability to speak, Proficiencies, Legendary Resistance, lair Actions, and Intelligence, Wisdom, and Charisma scores, as well as this action. Its Statistics and capabilities are otherwise replaced by those of the new form, except any Class Features or legendary Actions of that form.

Reactions

Prefect Counter. If the dragon is hit by an attack it can use a reaction to cause the attack to miss, if the attack was a critical hit the attack instead becomes a normal hit.

Legendary Actions

The greatwyrm can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The greatwyrm regains spent legendary actions at the start of their turn.   Detect. The dragon makes a Wisdom (Perception) check.   Attack. The dragon makes a claw or tail attack.   Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 30 ft. of the dragon must succeed on a DC 26 (8 + Prof + Str) Dexterity saving throw or take 12 (2d6 + 5) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.   Sun Burst (Costs 2 Actions). The dragon causes light to burst from the sphere created by this dragons Summon Dawn feature, this light heal any creature friendly to the dragon by 1d4 hit points, if the creature is in the dim light the dragon must subtract one from the roll, if it is not within the light it must subtract two from the roll. The light also damages any creature hostile to the dragon takes 1d4 radiant damage, if the creature is in the dim light the dragon must subtract one from the roll, if it is not within the light it must subtract two from the roll.  

Mythic Actions

If the greatwyrm's Draconic Awakening trait has activated in the last hour, it can use the options below as legendary actions.   Bite. The greatwyrm makes a bite attack.   Shattering Roar (Costs 2 Actions). The greatwyrm unleashes a magical roar. Each creature in a 120-foot-radius sphere centered on the greatwyrm must succeed on a DC 23 (8 + Prof + Cha) Constitution saving throw or take 19 (3d12) thunder damage and be incapacitated until the end of its next turn.   Summon Dawn (Costs 3 Actions). The greatwyrm uses its Summon Dawn action.

Lair Actions

On initiative count 20 (losing initiative ties), the dragon takes a lair action to cause one of the following effects; the dragon can’t use the same effect two rounds in a row:  

• The dragon glimpses the future, so it has advantage on attack rolls, ability checks, and saving throws until initiative count 20 on the next round.
• One creature the dragon can see within 120 feet of it must succeed on a DC 15 Charisma saving throw or be banished to a dream plane, a different plane of existence the dragon has imagined into being. To escape, the creature must use its action to make a Charisma check contested by the dragon’s. If the creature wins, it escapes the dream plane. Otherwise, the effect ends on initiative count 20 on the next round. When the effect ends, the creature reappears in the space it left or in the nearest unoccupied space if that one is occupied.

Gold dragons make their homes in out-of-the-way places, where they can do as they please without arousing suspicion or fear. Most dwell near idyllic lakes and rivers, mist-shrouded islands, cave complexes hidden behind sparkling waterfalls, or ancient ruins.

Regional Effects

The region containing a legendary gold dragon’s lair is warped by the dragon’s magic, which creates one or more of the following effects:  

• Whenever a creature that can understand a language sleeps or enters a state of trance or reverie within 6 miles of the dragon’s lair, the dragon can establish telepathic contact with that creature and converse with it in its dreams. The creature remembers its conversation with the dragon upon waking.
• Banks of beautiful, opalescent mist manifest within 6 miles of the dragon’s lair. The mist doesn’t obscure anything. It assumes haunting forms when evil creatures are near the dragon or other non-evil creatures in the mist, warning such creatures of the danger.

Gems and pearls within 1 mile of the dragon’s lair sparkle and gleam, shedding dim light in a 5-foot radius.   If the dragon dies, these effects end immediately.